Driving mechanism of mobile platens in presses



DRIVING MECHANISM OF MOBILE PLATENS IN PRESSES Filed April 16, 1946 H.'BOBST May 16, 1950* 2 Sheets-Sheet 1 fnyendar f/E/VR! B0557" fldorneysMay 16, 1950 H. BoBsT DRIVING MECHANISM OF MOBILE PLATENS IN PRESSES 2Sheets-Sheet 2 F'iled April 16, 1946 Patented May 16, 1950 DRIVINGMECHANISM OF MOBILE PLATENS IN PRESSES Henri Bobst, Lausanne,Switzerland Application April 16, 1946, Serial No. 662,589 InSwitzerland April 18, 1945 3 Claims.

The object of the present invention is a driving mechanism for a presshaving a movable lower platen and a fixed upper platen.

This mechanism is characterized by the fact that four pairs of togglelevers driving the platen are disposed each at one corner of a rectangleinside which is placed a crank shaft carrying two groups of opposedconnecting rods, the latter being adapted to act on the toggle levers bymoving simultaneously the knuckle joints connecting each pair of levers.

The annexed drawing shows an embodiment of a mechanism of this type,given by way of example and illustrates moreover an accessoryimprovement which is made possible by the proposed construction, andwhich is for this reason directly dependent therefrom.

Fig. 1 is a partial vertical cross section of a platen press of whichthe mechanism according to the present invention drives the lowerplaten.

Fig. 2 is a similar vertical cross section, at

' right angles to the plane of Fig. 1.

Fig. 3 refers to the aforementioned accessory improvement.

Figs. 4 and 5 show how the means controlling the transport of the blanksworked by the press are placed in relation to the new mechanismdescribed.

The press shown in Fig. 1 consists of the frame work in three parts I, 2and 3, of which the L middle part I constitutes the standard andsupports the upper fixed counter-platen 4 and guides the movable lowerplaten 5.

This latter is supported at its four corners by four pairs of togglelevers of which two pairs marked 5 and l are to be seen in Fig. 1. Theyform the limits of a rectangle which, in the example given, ispractically square, and they rest on a foundation 8 of the similarlyrectangular shape.

The knuckle joints connecting each pair of toggle levers are caught eachby one of the four connecting rods 9, ill, H and 12, divided in twogroups and opposed two by two on each side of the central toothed wheel!3 of the crank shaft It.

The crank shaft is placed inside the rectangle limited by the togglelevers, and forms in the described example, a cross shaped figure withthe driving shaft 15 carrying the endless screw it and driven fromoutside by means of the coupling fly-wheel ii.

The aforementioned members operate very simply:

The fly-wheel ll turning with the shaft 15, the endless screw l6 drivesthe toothed wheel [3 of 2 the crank shaft M, the rotation of whichconstrains the pairs of connecting rods 9, ID and ll, l2, to drive theknuckle joints of the toggle levers periodically towards the exterior,repelling them simultaneously and thus raising the movable platen 5 toexecute the pressing stroke.

Various important advantages are obtained by the foregoing arrangement:

The thrusts on the connecting rods repelling the toggle levers arepractically balanced. As a result, the different parts of the frame donot share the driving effort of the toggle levers as is the case indriving mechanisms using an outside crank, between the gear box of whichand the press per se there is generally considerable reaction stress.The guides for the movable platen may be reduced to a simple slide I8,guided by a die l9, as the lateral stress is very small. The thrusts dueto the working of the platen are absorbed by the press itself.Construction becomes less expensive and the reduced space necessitatedby the mechanism obviates dismantling of the machine for transport, itsmiddle part I being easily transported as a whole. Lubrication is alsosimplified.

Figs. 1 and 3 show moreover that the construction makes it possible toenclose easily the movable parts of the press inside a casing protectingthem against introduction of impurities and of dust arising from thework carried out, particularly when the press is used to cut outcardboard.

The frame I shutting in the mechanism on two sides, it suffices toprovide the sheet-iron plates 20 and 2! to close it on the other twosides. These plates, attached at their lower part to the foundation 8,extend upwards and are applied along the movable platen 5, against whichthey rest by means of the shoes 22 in leather, felt, etc. providing aneffective seal.

The result is that the space containing the toggle levers, theconnecting rods, the crank shaft, 2, part of the driving shaft and thegears, forms a practically closed space and that, as a result of thesuccessive upward and downward strokes of the movable platenconstituting the ceiling of said space, there will be a tendency to havetherein alternatively a vacuum and a plenum.

The plate 2| being provided with an air supply valve 23, with or withouta filter, and the plate 28 with a discharge valve 24, the whole will beventilated in the sense that at each ascent of the platen 5, freshand/or filtered air will enter the space occupied by the elements of thedriving mechanism, and that at each descent of the platen, this air willbe expelled the slight plenum resulting therefrom preventing dustinfiltration through the seals 22. The discharge valve could even bedispensed with and the air would escape by the joints seals 22.

This circulation of air of course also serves to cool the wholemechanism.

It would naturally be possible to add a pump to the whole, constantlysending air into the above mentioned space so as to create a plenumindependent of the movements of the platen 5.

In presses working at high speed, great rigidity is necessary betweenthe driving of the movable platen and the feed mechanism of the workedblanks. That is to say, it would be advantageous to establish a shortconnection by large dimensioned pieces.

In the example shown, it has been assumed that sheets of cardboard weretransported by gripper bars such as 25, conducted between the chains 26,driven by the shaft 21.

It is obvious that the distance between the crank shaft 14 and the shaft27 is very short and easily adaptable to a direct connection of thedrive mechanism of the toggle levers to that of the chains. This driveis here carried out by the crank cam 28 placed at the end of the crankshaft [4 (Fig. 2) and according to Figs. 4 and 5.

A connecting rod 29 articulated to the nob of the crank oscillates thetoothed segment 30 thereby imparting a to and fro movement to the pinion3! of the shaft 21, a coupling gear or clutch 35 actuated by the cam 28and the rod 32 of the fork 33 limits the movement of the shaft 21 in thedirection of the arrow 34 of Fig. 4.

The drawing clearly indicates the rigidity of this connection, reducedto its simplest form and using only short and large dimensioned parts.

It may be added that to regulate the pressure exerted by the togglelevers, it is advisable to rest these latter on the foundation '8 bymeans of keys such as 35 (see Fig. l), for example wedge shaped andadjustable as to position.

What I claim is:

1. In a press having a fixed upper platen and a rectangular movablelower platen, a set of toggles connected to each corner of and beneaththe lower platen, a crank-shaft located in the substantially rectangularspace between said sets of toggles and having four cranks arranged in0pposed pairs and a gear in the center thereof, a pitman connecting eachsaid crank to one of said sets of toggles, a common frame having closedvertical end and side walls for supporting said crank-shaft and togglesand enclosing at least 4. the lower portion of said toggles, a driveshaft penetrating from outside said frame into said space andoperatively connected to said gear, a casing resting on said commonframe and having vertical end and side walls extending the walls of saidframe, said casing enclosing all the upper portion of said toggles andat least part of said lower platen and engaging frictionally the sidefaces of said lower platen, a chain shaft, a direct driving connectionbetween said crank shaft and said chain shaft, endless chains driven bysaid chain shaft, and gripper bars connected to said chains forconveying work pieces to the press.

2. A press according to claim 1 wherein said direct driving connectioncomprises a crank nob rotatable with said crank-shaft, a connecting rodactuated by said nob, a toothed segment connected to and oscillatable bysaid rod about an axis parallel to said chain shaft, a gear on saidchain shaft engaging said segment, a clutch interposed between said gearand chain shaft, and a cam on said crank-shaft controlling engagement ofsaid clutch in one direction of oscillation of said segment anddisengagement thereof in the other direction.

3. A press according to claim 2 including a cam-follower leaning on saidcam, a rod rotatable with said cam-follower, and a crank on said rodconnected to a movable part of said clutch, whereby rotation of said rodin response to actuation of said cam-follower by said cam will disengagesaid clutch in one direction of rotation of said rod and engage it inthe other direction.

HENRI BOBST.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 215,872 Bowdoin May 27, 1879239,475 Exley Mar. 29, 1881 247,613 Carson Sept. 27, 1881 395,857 TaylorJan. 8, 1889 423,064 Littlejohn Mar. 11, 1890 511,785 Melvin Jan. 2,1894 783,342 Wilfrey Feb. 21, 1905 1,110,977 Welch Sept. 15, 19141,485,546 Affelder Mar. 4, 1924 1,584,230 Knight May 11, 1926 1,926,576Beatty Sept. 12, 1933 2,081,175 Friden May 25, 1937 2,413,554 Evers Dec.31, 1946 2,425,040 Luehrs Aug. 5, 1947

